This invention relates to systems for producing polyolefins. In one of its aspects this invention relates to the production of olefin polymers using a loop reactor. In another of its aspects this invention relates to the recovery of soluble catalyst components from effluent polymer slurry. In another of its aspects this invention relates to integrating a wash column apparatus and polymer slurry settling leg into a pipe-loop reactor system. In yet another aspect of the invention it relates to an integrated system for recovery of unreacted monomer from polymer slurry effluent with purification of the recovered monomer and recycle of the purified monomer to a wash column attached to the reactor loop in a pipe-loop reactor system.
The use of pipe-loop reactor systems in the polymerization of olefin monomer is well known in the art. High productivity catalysts that produce low levels of soluble polymers have recently been developed for use in pipe-loop reactors. Using these catalyst systems, it has been discovered that a wash column with settling leg can be attached directly to a pipe-loop reactor thereby eliminating conventional contactors and wash column generally associated with such a system. This combination of equipment permits both a reduction of overall equipment investment and an improvement in efficiency in recovery of catalyst components for effective use in the polymerization system thereby improving the economics of using the catalyst system.
It is therefore an object of this invention to provide a pipe-loop reactor equipped with an attached wash column and settling leg. It is another object of this invention to provide an apparatus for controlling flow of settling polymer into the wash column. It is another object of this invention to provide a method for recovering soluble catalyst from the effluent polymer slurry of a pipe-loop reactor back into the reactor. It is still another object of this invention to provide an integrated system for recovery of propylene monomer from the reactor effluent in a propylene polymerization with recycle of at least a portion of the propylene monomer as wash liquid in a wash column attached to a pipe-loop reactor.